The disposing of liquid manure from cattle, pig and poultry farm operations has been a problem for many years. The disposal of these products must be consistent with prevailing environmental standards. It is recognized that separating fresh solids before their polutive elements dissolve in the liquid is important. Thus, an objective of today's manure handling system is to remove the fresh solids from the liquid manure slurries to reduce the pollutant and nutrient content of the manure, thereby prolonging the life of a manure lagoon and other storage facilities and improving the effectiveness of biological treatments, and minimizing the risk of creating an environmental nuisance.
Solids separated from the liquid manure may be spread on farm land; used as bedding materials; or may be mixed with feed ingredients to produce rations for ruminant animals. The solids may also be granulated and bagged and sold as commercial compost.
Typical of the equipment used today to separate solids from liquids in manure is a screw press separator, as illustrated in FIGS. 8 and 9. Such equipment is available from Fan Engineering, U.S.A., Inc., Columbus, Ohio.
In the prior art auger separator 10 shown in FIGS. 8-12, material is fed into the auger through an inlet 12 and discharged through a pressure gate 14 at the outlet end 16. A plug zone 18 exists between the outer end 20 of flighting 22 and the pressure gate 14. Weights 24 on an arm 26 allow for the pressure required to open the gates 14 to be varied.
The flighting 22 has a uniform pitch from the inlet end to the end 20, and depends on pressure build-up against the pressure plates 14 to cause liquid to be separated from solid material by being forced through openings 30 in an inner auger tube 32. The liquid is collected in an outer tube 34 and drained from the auger separator 10 through an outlet conduit 36.
The problem with the prior art auger separator of FIGS. 8 and 9 is that insufficient liquid can be separated from the solid material. The pressure required to open the pressure gates 14 can only be set so high, and beyond that critical point the system will shut down and become inoperative. As noted, insufficient pressure can be applied to the slurry material to separate out a high enough percentage of liquid before the entire system is shut down. It is thus apparent that what is needed is an improvement to the auger separator system that allows for a higher percentage of liquid separation from the solids.